/*********************************************************************
 * Copyright (C) 2005 Andrew Khan
 * <p>
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * <p>
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 * <p>
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 ***************************************************************************/

package jxl.biff;

import jxl.WorkbookSettings;
import jxl.common.Logger;

/**
 * Helper to get the Microsoft encoded URL from the given string
 */
public class EncodedURLHelper {
    /**
     * The logger
     */
    private static Logger logger = Logger.getLogger(EncodedURLHelper.class);

    // The control codes
    private static byte msDosDriveLetter = 0x01;
    private static byte sameDrive = 0x02;
    private static byte endOfSubdirectory = 0x03;
    private static byte parentDirectory = 0x04;
    private static byte unencodedUrl = 0x05;

    public static byte[] getEncodedURL(String s, WorkbookSettings ws) {
        if (s.startsWith("http:")) {
            return getURL(s, ws);
        } else {
            return getFile(s, ws);
        }
    }

    private static byte[] getFile(String s, WorkbookSettings ws) {
        ByteArray byteArray = new ByteArray();

        int pos = 0;
        if (s.charAt(1) == ':') {
            // we have a drive letter
            byteArray.add(msDosDriveLetter);
            byteArray.add((byte) s.charAt(0));
            pos = 2;
        } else if (s.charAt(pos) == '\\' ||
                s.charAt(pos) == '/') {
            byteArray.add(sameDrive);
        }

        while (s.charAt(pos) == '\\' ||
                s.charAt(pos) == '/') {
            pos++;
        }

        while (pos < s.length()) {
            int nextSepIndex1 = s.indexOf('/', pos);
            int nextSepIndex2 = s.indexOf('\\', pos);
            int nextSepIndex = 0;
            String nextFileNameComponent = null;

            if (nextSepIndex1 != -1 && nextSepIndex2 != -1) {
                // choose the smallest (ie. nearest) separator
                nextSepIndex = Math.min(nextSepIndex1, nextSepIndex2);
            } else if (nextSepIndex1 == -1 || nextSepIndex2 == -1) {
                // chose the maximum separator
                nextSepIndex = Math.max(nextSepIndex1, nextSepIndex2);
            }

            if (nextSepIndex == -1) {
                // no more separators
                nextFileNameComponent = s.substring(pos);
                pos = s.length();
            } else {
                nextFileNameComponent = s.substring(pos, nextSepIndex);
                pos = nextSepIndex + 1;
            }

            if (nextFileNameComponent.equals(".")) {
                // current directory - do nothing
            } else if (nextFileNameComponent.equals("..")) {
                // parent directory
                byteArray.add(parentDirectory);
            } else {
                // add the filename component
                byteArray.add(StringHelper.getBytes(nextFileNameComponent,
                        ws));
            }

            if (pos < s.length()) {
                byteArray.add(endOfSubdirectory);
            }
        }

        return byteArray.getBytes();
    }

    private static byte[] getURL(String s, WorkbookSettings ws) {
        ByteArray byteArray = new ByteArray();
        byteArray.add(unencodedUrl);
        byteArray.add((byte) s.length());
        byteArray.add(StringHelper.getBytes(s, ws));
        return byteArray.getBytes();
    }
}
